Electron discharge device and circuit



June 22, 1937. c, H, BR WN 2,084,476

ELECTRON DISCHARGE DEVICE AND CIRCUIT Filed Aug. 29, 1936 OUTPl/TMODUMTION 1 INPUT INVENTOR CHARLES H. BROWN our ur BY MM ATTORNEYPatented June 22, 1937 PATENT OFFICE ELECTRON DISCHARGE DEVICE ANDCIRCUIT Charles H. Brown, Brooklyn, N. Y., assignor to Radio Corporationof America, a corporation of Delaware Application August 29, 1936,Serial No. 98,446

Claims. (Cl. 179-171) This invention relates to high frequency electrondischarge device oscillators, and modulation circuits for same.

It is known to produce oscillations by employing a stream of electronswhich are caused to travel in a curvedpath so as to cross itself wherebythere is obtained a periodically interrupted stream of electrons. Thismode of operation is quite similar to the functioning of the air streamin an air whistle and has been called the electron whistle principle.For a more detailed description thereof, reference is made to UnitedStates Patent No. 2,001,133, granted to Clarence W. HansellMay 14, 1935.

The present. invention provides an improved electron discharge devicecircuit arrangement employing the electron whistle phenomenon, and isfurther explained in connection with the accompanying drawing whereinFigs. 1 and 2 show two different embodiments of the invention.

In Fig. 1, there is shown, partly in section and partly schematic, anoscillation generator system in accordance with one embodiment of theinvention, comprising an evacuated metallic device I having a tube 6, atone end of which is a cathode 2 energized by a source of heating currentID. A metallic shield 5 is maintained, together with the envelope ofdevice I, at a suitable negative potential by means of source II whichserves to concentrate the flow of electrons emanating from the cathodetoward the opposite end of tube 6. At the other end of tube 6 there ispositioned a grid or mesh afiair 3 located at the opening of a flared,tubular, circular portion 4 which, in turn, causes the electrons passingthrough the grid 3 to travel in a curved path so as to cross itself andthus interrupt the stream entering the flared shell. A second. grid 1 ispositioned within the shell 4 at a point somewhat removed from theentrance to the shell, and both grids are coupled to opposite terminalsof a suitably tuned resonant circuit comprising an inductance coil 8 anda condenser 9, to the coil of which is coupled a source of potential I!for maintaining the two grids at a high positive potential relative tothe cathode. Suitable insulating bushings or mountings l3 serve toinsulate the cathode and grids from the metallic sides of the device. I

Although portion 4 is made of metal and maintained at a negativepotential determined by source II, it will be understood that it mayconsist of insulation, such as glass, in which case various portions ofthe inside of the shell will automatically assume the correct potentialsfor suitable operation of the device. It should also be understood thattuned circuit 8, 9 is merely illustrative of any resonant circuit andthat, if desired, a resonant line might be employed instead, or thecondenser 9 may be omitted and the distributed capacitance of the coil 8relied upon to complete the tuned circuit.

The operation of the device is as follows:

Electrons emanating from the cathode 2 are negatively charged and areattracted towards the circular shell 4 by the positively charged grid 3.These electrons travel in a substantially straight line along portion 6of the device and follow, in general, the path of the dotted lines. Theenvelope of the electron discharge device I repels the electron streamand confines same to the interior of the tubular passageways. Most ofthe electrons attracted by the positive-charged grid 3 pass through theapertures thereof with high velocity and follow the inner periphery ofthe shell 4 and are further propelled on their way by the positivecharge on grid 1, after which, due to their momentum, they cross thepath of the electron stream entering the shell 4, and in this way thestream entering the shell is interrupted due to the mutual repulsionbetween electrons. In order to enable the returning electrons to crossthe oncoming stream exactly at right angles, and produce a cleaninterruption, there is preferably employed a slight extension M whichprotrudes within the interior of the device, in the manner shown in thedrawing.

This mode of operation is quite analogous to that of an ordinary air orsteam whistle, and a comparison between the two is herein made merely toaid in a better understanding of the invention.

The frequency of interruption of the electron stream and the frequencyof oscillations produced in the tuned circuit 8, 9 are dependent on suchfactors as the grid voltages and the dimensions of the tube. Theresonance frequency of the tuned circuitwill, of course, suitablyconform with the transit time of the electrons betweenthe two grids 3and 1. By means of such an arrangement it is possible to produceextremely high frequencies in the output circuit which may comprise atransmission line or any suitable utilization device.

Fig. 2 discloses a modification of the circuit of Fig. 1 and shows onemethod of modulating the high frequency oscillations produced inaccordance with the invention. In this embodiment, four positive gridsare employed within the interior of shell 4, adjacent grids beingconnected to difierent tuned resonant circuits. A

suitable speech or otherinput circuit is shown electromagneticallycoupled to the coil IQ of a resonant circuit is, to whose terminals arecoupled the diametrically oppositely located grids l5, ll, The outputcircuit in this case is coupled to the tuned circuit 22 which isconnected to the other two grids l6, I8. 1

Obviously more elaborate arrangements may be employed for concentratingthe electron stream within tube 6 and/or circular shell 4, and sucharrangements may consist of suitably charged tubular or'disc electrodeshaving apertures, or plates, on opposite sides of the electron stream inthe manner employed in cathode ray devices.

What is claimed is:

1. In a high frequency system, an electron discharge device comprising acathode for emitting a stream of electrons, an element for attractingsaid electrons and enabling same to pass by said element with highvelocity, means for subsequently causing said stream of electrons totravel in a curved path so as to cross itself, a grid in said curvedpath, and a resonant circuit coupled between said element and grid.

2. In high frequency apparatus comprising an electron emitting elementand a pair of spaced cold electrodes, the method of producing highfrequency oscillations which comprises unidirectionally propelling astream of electrons in the form of a beam from said element past saidpair of cold electrodes, whereby there is produced a diflerence inpotential between said pair, deflecting said stream of electrons in acurved path so that the stream crosses itself at an angle, therebyinterrupting the oncoming stream, and repeating said cycle of operationsto produce oscillations of the desired frequency.

3. In high frequency apparatus, an electron discharge device comprisinga cathode for emitting a stream of electrons, and means for making saidstream of electrons cross upon its own path at an angle periodically,thereby interrupting said stream, including a pair of spaced grids inthe path of travel of said stream, a tuned resonant circuit coupled tosaid grids and a translating circuit coupled to said tuned circuit.

4. A system in accordance with claim 3, characterized in this that saidtranslating circuit is a utilization circuit.

5. A system in accordance with claim 3, characterized in this that saidtranslating circuit is a speech input circuit.

6. In combination, a device for producing high frequency oscillationscomprising a cathode for emitting a stream of electrons, a first pair ofspaced grids in the path of travel of said stream for controlling theflow of said electrons, a source of potential for maintaining said gridsalways at a positive potential relative to said cathode, 1| and meansfor causing the stream of electrons to travel in a curved path so as tocross itself, said means including a curved shell which has a potentialat least as negative as said cathode,

a second pair of spaced grids at least one of l: which is locatedintermediate the grids of said first pair, means for maintaining saidsecond pair of grids always at a positive potential relative to saidcathode, a tuned circuit connected to each par of grids, an inputcircuit connected to one 2( of said tuned circuits and an output circuitconnected to the other tuned circuit.

'7. A system in accordance with claim 1, including means forconcentrating into a stream the electrons emanating from said cathode.

8. In an electron discharge device, means for causing a stream ofelectrons to take a substantially circular path, two spaced grids insaid circular path, a source of potential for maintaining both of saidgrids always at a positive potential relative to said stream, and atuned circuit coupled between said grids.

9. In an electron discharge device, means for unidirectionallypropelling a stream of electrons in a circular path, including twospaced grids in said circular path, a source of potential formaintaining both of said grids always at a positive potential relativeto said stream, and a tuned circuit coupled between said grids.

10. In an electron discharge device, means for unidirectionallypropelling a stream of electrons in a circular path, including foursubstantially equally spaced grids in said circular path, means formaintaining all of said grids always at a positive potential relative tosaid stream, a tuned circuit coupled to one pair of oppositely locatedgrids, and another tuned circuit coupled to the other pair of grids.

CHARLES H. BROWN.

